The final six chapters of the Bhagavad Gita are primarily focused on taking the “big picture” view that we have been offered in the earlier chapters, and addressing the application of the principles into the details of life and action. The Gita here is transforming what would otherwise be a philosophical doctrine into a practical and detailed methodology. Arjuna has been convinced of the correctness of Sri Krishna’s viewpoint. At the same time, he has immediately grasped the issue that without some clear and detailed understanding he would again find himself lost in the play of forces and the currents of life. He therefore requests that the general knowledge, and the vision he has been vouchsafed, be turned into a detailed understanding of the way the Purusha interacts with Prakriti and the practical tools he would need to exert leverage on the reactions of his outer nature.
This interaction of Purusha and Prakriti constitutes one of the primary questions to be addressed, but the Gita also takes up the question of the three Gunas of Nature, the method of their interaction and how they constitute all the actions of life, and the way to gain ascendency over their action. The Gita provides possibly the best detailed explication of the Gunas that has been developed and these final six chapters delve in detail into how to use this knowledge to gain liberation while continuing to act with vigor in the world.
Sri Aurobindo outlines the questions to still be taken up: “All life, all works are a transaction between the soul and Nature. What is the original character of that transaction? what does it become at its spiritual culminating point? to what perfection does it lead the soul that gets free from its lower and external motives and grows inwardly into the very highest poise of the Spirit and deepest motive-force of the works of its energy in the universe?”
The Gita draws upon its wider synthesis of Vedanta, Sankhya and Yoga to distill out a practical guidebook for action.
Sri Aurobindo, Essays on the Gita, Second Series, Part II, Chapter 13, The Field and Its Knower, pp. 395-396